Two tribes became one on Tuesday as Bernie Sanders appeared side-by-side with Hillary Clinton at a joint rally that marked a poignant reconciliation between the once bitter foes in the Democratic primary, reports UK’s The Guardian.

Amid some of his most passionate supporters in Portsmouth, New Hampshire, Sanders officially endorsed to the former secretary of state in her battle against Donald Trump after a series of policy compromises were hammered out over the weekend.

“I have come here to make it as clear as possible as to why I am endorsing Hillary Clinton,” Sanders said to exuberant applause, “and why she must become our next president.”

Sanders prompted one or two boos from the emotional crowd of his supporters when he spelled out the mathematical realities to them once and for all, but left no doubt where he now stood.

“I am proud of the campaign we ran here in New Hampshire and across the country,” he said. “Our campaign won the primaries and caucuses in 22 states and when the roll call of the Democratic national convention is announced, it will show that we won almost 1,900 delegates … far more than almost anyone thought we could win.

“But it is not enough to win the nomination. Secretary Clinton goes into the convention with 389 more pledged delegates than we have and a lot more super-delegates,” he said, before acknowledging clearly for the first time, before conceding that Clinton had won the nomination process “And I congratulate her for that. Secretary Clinton has won the Democratic nomination.”

“I congratulate her for that,” he added warmly, putting an arm on Clinton’s shoulder. “I intend to do everything I can to make certain she will be the next president.”

At times, Sanders’ remarks sounded like the standard stump speech he had delivered to some 1.4 million Americans at rallies this year, but it had a very different conclusion.

“The profound lesson I have learned is that this campaign is not about Hillary Clinton, Bernie Sanders or Donald Trump, this campaign is about the needs of the American people and addressing the very serious crises that we face,” he said.

“There is no doubt in my mind that as we head into November, Hillary Clinton is by and far away the best candidate to do that.”

He also praised Barack Obama for the economic progress made during his two terms, but added: “I think we can all agree much much more needs to be done. Too many Americans are still being left out, left behind and ignored … In the richest country in the history of the world, there is too much poverty, there is too much despair.”

Sanders signed off by vowing to go on the road in support of Clinton’s presidential bid and praised her for breaking precedent as a first lady, helping to lead the fight for universal healthcare, while describing her as “a fierce advocate for the rights of our children”.

He closed, thumping the lectern and proclaiming: “Hillary Clinton will make an outstanding president and I am proud to stand with her today.”

A tiny handful of Sanders supporters left the room waving placards as Clinton took her turn at the lectern, but otherwise there was warm applause from all for a relaxed-looking candidate.

“I can’t say how much more enjoyable this election is going to be now that we are on the same side,” she said. “Because you know what? We are stronger together.

“Now we are joining forces to defeat Donald Trump and together build a future that we can all believe in,” added Clinton, who smiled and nodded when her former adversary had described the revised Democratic manifesto as the most progressive in history.

“He has inspired a generation of people of who care deeply about this country,” said added, thanking Sanders for his “lifetime fighting injustice”.

Clinton quickly pivoted however to addressing the spate of recent police killings and attacks in Dallas, calling for national guidelines on the use of force by police offices and training against “implicit bias”.

“These have been difficult days for America,” she said. “Rebuilding the frayed bonds of trust and respect between law enforcement and the communities they serve will require contributions from all of us and we have to start by listening to each other … We have to do something to heal these wounds.”

Some anti-Clinton protesters outside the packed school hall appeared unconvinced by the truce, but the vast majority of the large Sanders crowd mingled enthusiastically with Clinton supporters in scenes that were far removed from the partisan rancour that characterised their primary fight.

Sanders won the New Hampshire primary in February by a large margin but has been under pressure to endorse Clinton ever since his already difficult path to the nomination disappeared entirely after the California primary last month.

Before the erstwhile rivals spoke, Bill McKibben, an environmentalist and leading Sanders surrogate, warmed up the crowd by heralding “the excellent work by the platform teams over the past few weeks” in making sure the campaign’s ideas were now reflected in the Democratic agenda.

“We’ve gone from an all of the above energy policy to a platform that instead gives clear priority to the awesome power of the wind and the sun,” he said.

“Secretary Clinton, we wish you godspeed in the fight that now looms,” added McKibben.

“We are all here today to send a powerful message that our party is united and strong,” said Maggie Hassan, the New Hampshire governor, to loud cheers and the occasional rogue shout of “Bernie” from the crowd.

Jim Dean, chair of Democracy for America, another group backing Sanders, thanked everyone who worked on both of these campaigns for “keeping it real” and called on the crowd: “Let’s get behind Secretary Clinton.”

Loud chants of “Bernie, Bernie” from the hall were met with an almost as loud responding cry of “unity, unity”.